Abstract: The simulation results shows that pilot injection, intake preheating, main injection advance angle have a big impact on ignition performance of diesel engine. After using pilot injection, the average cylinder pressure and temperature, and the accumulated heat release increased, ultimately the fuel efficiency had been improved. By using the intake preheating, combustion efficiency had been improved for combustible mixture gas formed easily and combustion conditions significantly improved in cylinder. Besides, an appropriate main injection advance angle could improve the combustion of ignition delay period and increased the engine power and fuel efficiency.

Abstract: In order to study the effect of hot EGR on combustion characteristic of hydrogen internal combustion engine (HICE), experimental study was taken on a 4 cylinder, 2.0L HICE. The speed was 3000rpm, and the throttle was fully open, the load was adjusted through quality regulation. When the hydrogen flow ratio was 2.79kg /h, the ignition advanced angle was optimized as maximum brake torque (MBT) timing, then the EGR valve was opened, and EGR valve was adjusted to control the flow of exhaust gas that back into the intake manifold. The test results show that: as the EGR ratio changing from 0(the EGR valve is fully closed) to 43.8%(the EGR valve is fully opened), the in-cylinder pressure is decreasing with the EGR ratio increasing; the coefficient of variation in indicated mean effective pressure (imepCOV) is not changing significantly at high load conditions, changing range is less than 1%; CA50 is postponed from 11.8oCAto15.2 oCA with EGR ratio increasing.

Abstract: The combustion models for HCCI engines which based on CHEMKIN4.0 have been modified and integrated, and a simulation system including a single-zone model has been developed, which could rapidly bring accurate information for prediction of ignition point and control of emissions.

Abstract: A simulation model of the linear engine system is built in this paper. The cylinder pressure data obtained through engine experiments is used to validate the accuracy of the simulation model. Based on the model, the combustion characteristics and external characteristics of the linear engine system were studied. And the maximization model is used to find an optimum operating region of the linear engine. The results show that, as the air fuel ratio(AFR) decreases under a steady engine speed, both the cylinder pressure and brake power increase first and then decrease, reaching their peak value when the AFR is 12. Under this AFR, the maximum brake power is 16.83kW at 6500rpm. Meanwhile, the fuel economy and the power performance reach the optimum combination within 5200rpm and 6500rpm.